SECTION SEVEN 



12. Drain off excess stain; then wash for five seconds in each 

 of two changes of distilled water. 



13. Drain and leave to dry, protected from dust, in the air or in 

 the incubator. 



Results: 



Elementary bodies, blue. Cell nuclei, pink. Cell protoplasm, 

 green. 



Reference: Herzberg, K. (1934), Zentrlh. f. Bakt. Orig., 131, 358-66, 

 *' Viktoriablau zur Farbung von filtrierbarem Virus ". 



WRIGHT'S STAIN 



For general differentiation of blood corpuscles; for mal- 

 aria parasites, trypanosomes, etc. 



This stain is extensively used in America instead of Leishman 

 stain, which is generally preferred by British workers. 



Best results are obtained with very thin films, and the distilled 

 water used should be buffered to pH 6 •5-7-0. 



Technique: 



Fixation is unnecessary unless the films are to be kept for any 

 length of time before staining, in which case they should be fixed 

 for five minutes with pure methyl alcohol ; then blotted and dried 

 at room temperature. 



1. Place I ml. of the stain on a dried blood film and leave it to 

 act for one minute; then add 2 ml. distilled water and rock the 

 slide gently to mix. 



2. Allow this diluted stain to act for three to five minutes; then 

 pour off and wash with distilled water until the thin portion of the 

 films appears pink to the naked eye. 



3. Pour off excess stain; blot and dry at room temperature. 



Results: 



Erythrocytes, yellowish red. Polymorphonuclears : dark purple 

 nuclei, reddish violet granules, pale pink cytoplasm. Eosinophiles : 

 blue nuclei, red to orange-red granules, blue cytoplasm. Baso- 

 phils : purple to dark blue nuclei, dark purple to black granules. 

 Lymphocytes : dark purple nuclei, sky-blue cytoplasm. Platelets, 



405 



